Beginner Vegetables: First-time veggie garden questions

I want to plant a first-timers easy and simple raised veggie garden next year. It's just me eating this, so I'm not attempting anything I don't eat already and love -- so one crookneck yellow squash plant, one zuchinni plant. I don't have to grow enough to provide everything, just want to try and see what happens. I can add more if this works out. I have perennial flower beds I'm proud of. But seeding and transplanting and harvesting veggies are new concepts for me.

I'm starting now by building the raised beds. The ground is compacted clay and gravel so I'm going UP. I figure to plant close together but wasn't planning on going so far as stringing for square foot gardens... that could change over winter.

The beds will be 16" tall and 3'x32', 4'x20', and 4'x16'. The first bed will run roughly NE to SW and is up against a chainlink fence. The other two will run perpendicular and roughly SE to NW and I can walk all the way around them. They will all get sun from 11a to twilite. The beds can be 8-16" deep, that's up in the air now. I'll bottom them with wet cardboard to encourage earthworms (although with the ground, I'm not hopeful). And I'll line the corners/sides with weedcloth to keep the soil in.

Any advantage to several 4x4 instead of along 4x20?

I have vine frames I can slant over the bed to shade cool crops. And access to a LOT of greenhouse mesh tarps if that is needed.

Suggestions for mulch? I'm not philosophically opposed to plastic, but something like straw might be "useful" to the soil later... Thoughts?

I plan on filling the beds this fall, watering well, and covering with black plastic... the idea to "cook" the soil in the sun and keep out weeds until I take the plastic off in the spring, and add more soil after it settles. Is the plastic a good idea or no?

Sounds like you have everything pretty much figured out. Only need a little encouraging.
I like the mixer for your topsoil, but thats what I always do. Mix together whatever I have on hand. I do add a little slow release fertilizer at planting/sowing time.
I've never been sold on the companion planting. I've tried it (and still do) but have never seen a sensible increase in yield or a decrease in pest. Its just fun to try.
The main practice I do is crop rotation which may not be necessary if you change your raised bed soil every year. (I hear some people do. Me, I ain't got the time or resources. LOL)
All the plants you listed will do fine in a raised bed. The only drawback is you will have to irrigate more often, but some people like that because its harder to overwater.
The point is to enjoy it and not be discouraged by any drawbacks. Heck, I lost 90% of my pumpkin patch to cucumber beetles and wilt this summer. With the frustration, I'm sure I'll still grow pumpkins again.
With what you've shared, I think you'll be just fine. Good luck and happy harvesting

A 20 foot bed seems short enough. When you wnat to walk around it to get at the other side, you never need to walk more than 10 feet.

Personally I like narrow beds (30" - 36" rather than 48"). They are easier to handle from one side. You can let squash or tomatoes drape themselves over the side and expand without crowding your growing area.

If you can give yourself a 12" walkway between the chainlink fence and your bed, you will be able to sow or transplant and weed more easily.

Were you going to use the fence as a trellis?

If the beds dry out too fast, you can line the inner corners (or all of the walls) with ehavy plastic. water seems to evaporate out of my beds right through the walls!

I think the main downside of narrow beds is that weeds are harder to remove when they grow right up against the wall.

>> sugar snap peas

If you like those, consider Snow Peas. Most people eat the young thin tender pods, but Oregon Sugar Pod II works great if you let the pods grow big and fat and bulging with peas. Still very sweet and almost as tneder, and 4-5 times as much food!

>> lettuces, spinach

If you like those, consider Bok Choy (Pak Choi) or the slightly harder to grow Chinese Cabbage (Michili). They make great salad when young, and can be eaten as steamed or boiled greens or soup later, or sauteed or stir-fried

I would find peppers and potatoes difficult.

I love bark mulch. It is also a good soil amndment: lasts longer than wood chips, and causes much less nitrogen deficit (if any). "Nuggets" make better mulch becuase they6 are bigger chunks. "Mulch" or bark fines is usually finer, with lots of powder and fibers - and often dirt, sticks and weed seeds. Cheap HD mulch may not be a bargain !

From your list, I drool over the aged cow manure, pine bark fines and mushroom compost. For really good garden soil, you might want to keep the % of clay below 30% or 25%. That menas that, if you started with pure gooey clay, that you maut add two or three times as much "other stuff" to make it great. Thus a 16" bed might want 4" of clay plus 12" of other stuff.

Of course, what poor soil usually needs most is organic matter. And that OM will be eaten by soil microorganisms. So you may need to replenish as much as 50-75% of the soil every year for the first few years! One crude rule of thumb is that an inch or two (or more) of compost every year is very good for a bed.
-

I also have clay soil, but when I make an RBm, I also try to "encourage" the soil underneath it to loosen up and become accessible to rotts over the years. I break it up a little and mixi in some compost or manure. I also like to mixm in at least a little long-lasting drainage-enhancer, something chunky like bark or grit. I imagine that it makes it easier for worms to come in, and for bed drainage to penetrate and soften the clay.

I also make sure that the soil beneath the bed won't become waterlogged due to poor drainage. I position them on a little slope, and/or cut a little slit trench down from the floor of the bed to some lower spot in the yard. This is also intended to make the soil UNDER the bed avbailable to roots and worms. Over a few years, I epxect roots and worms to improve the soil under my bed, making its effective depth greater by as many inches as those roots feel they need.